sts-suite 0.1.1

Terminal debugger for Feetech STS3215 smart serial bus servos

sts-suite

Terminal debugger for Feetech STS3215 smart serial bus servos.

Requirements

• Python 3.10 or newer
• A USB-to-TTL adapter wired to the servo bus

Install

With uv:

uv tool install sts-suite

Or with pip:

pip install sts-suite

Run

sts

Pick a serial port and baud rate. The debugger opens. The last choice is saved to ~/.cache/sts-suite/last.json.

If no motors respond, hit Baud sweep in the port picker and it will try every preset and pick the one with the most motors.

Main screen

Left sidebar: motors on the bus. Toggle multi-select with ctrl+space; goal and nudge then drive the whole selection via sync_write in one packet.

Right side: a watch strip with the always-visible vitals, then the full register table. Enter on any RW row pops an edit modal with a description, range, units, and a dropdown for enum registers.

Screens

Key	Screen
?	Help overlay
o	Oscilloscope: live plot of position / speed / load / current
w	Waveform generator: sine, square, triangle, step
v	Grid view: every motor on one screen
d	Diff against a saved state snapshot
Ctrl+L	Preset loader: apply a JSON of register values

Keybindings

Key	Action
q	Quit
r	Rescan bus
t	Toggle torque on selected (or all selected)
!	E-STOP: broadcast torque off to every motor
space	Full refresh
Ctrl+Space	Toggle multi-select on highlighted motor
g	Focus goal / speed input
k / j	Nudge +5 / -5 (auto-scales per mode)
l / h	Nudge +50 / -50
c	Center: goal to 2048 or speed to 0
Enter	Edit selected register (RW only)
x	Movement test on selected motor
s	Save JSON snapshot of every motor
Ctrl+R	Reboot selected motor

Modes

The control bar adapts to the selected motor's mode register.

Mode	Name	Target	Range	Nudge scale
0	position (servo)	goal_position	0 to 4095	1
1	wheel (continuous)	goal_speed	-4000 to 4000	10
2	PWM (open-loop)	goal_speed	-1000 to 1000	5
3	step	goal_position	-32768 to 32767	20

Status register

Bit flags decoded in the register table and watch strip.

Tag	Meaning
VOLT	voltage out of range
ANGLE	angle limit exceeded
HOT	overheat
CURR	overcurrent
OVLD	overload

Snapshot file

s writes sts-state-YYYYMMDD-HHMMSS.json in the current directory with every register value for every motor on the bus. Load one with d to diff against the current live readings.

Preset file

Presets live in any JSON file with a top-level registers map:

{
  "registers": {
    "p_coefficient": 32,
    "i_coefficient": 0,
    "d_coefficient": 0,
    "torque_limit": 800,
    "acceleration": 30,
    "max_temperature_limit": 70
  }
}

Ctrl+L applies every RW field to the selected motor; EEPROM fields are unlocked and re-locked automatically.

Performance

• Live tick reads SRAM 40-70 in one read_raw_data call (single round trip per refresh).
• Full refresh reads EEPROM 0-39 plus SRAM 40-70 as two bulk reads instead of 26.
• Serial I/O runs in a worker thread; a stuck motor can't freeze the UI.
• Multi-motor writes use sync_write_raw_data so N motors update in one packet.

Stack

• Textual and textual-plotext for the UI
• rustypot for the Feetech protocol over serial

License

Apache License 2.0. See LICENSE.